Defining Evolution

I must take issue with Brian Solik’s definition of evolution in his letter. Mr. Solik quotes a correct “typical definition from a PBS website,” but as he states, that is a definition not of evolution but of “the evolutionary process of speciation.” The process of speciation is an example of an evolutionary process. It is not a synonym of evolution. In biology, evolution, derived from the Latin verb evolvere, to unroll or unfold, is defined in dictionaries and standard textbooks as, for example, “change in the properties of groups of organisms over the course of generations” and “passed via the genetic material from one generation to the next” (quotations from the excellent textbook Evolution by Douglas J. Futuyma of the State University of New York at Stony Brook).

Not unexpectedly, Joel Achenbach ’82, in his accurate PAW article, and the scientists Peter and Rosemary Grant correctly use the term evolution. Mr. Solik points out correctly that the Grants study what is “sometimes called microevolution.” However, microevolution is one kind or aspect of evolution. Mr. Solik states falsely, perhaps inadvertently, that it “is not evolution at all.” Everyone is familiar with microevolution because that term encompasses the genetic changes that we inherit from our grandparents and parents. As Futuyma put it succinctly, “Biological evolution may be slight or substantial: It embraces everything from slight changes in the proportions of a gene within a population to the alterations that led from the earliest organism to dinosaurs, bees, oaks, and humans.” From their “natural laboratory” at Daphne Island, the Grants have significantly advanced understanding of how microevolution occurs and its broader impacts on populations and species.